Locks on the Fox. The Fox River once crashed over waterfalls and surged through rapids, descending 170 feet over 39 miles between Lake Winnebago and Green Bay. Appleton and Kaukauna were founded near especially rough passages and steep drops. In the 1850s, European settlers sought to make the Fox River safe for boat traffic and to harness its power for mills and factories. That required dams, canals, and locks. Dams regulated the water flow, and canals provided passages around obstacles. Locks were essential where the river dropped steeply. Locks gently lower a boat when it travels downstream or lift it when it goes upstream. The state of Wisconsin put the Fox River Improvement Company in charge of the construction work in 1853. By 1856, the company had built locks along the entire river, making it navigable from Menasha to DePere. These changes further increased the Fox River's importance as a transportation corridor. Today, the locks on the Lower Fox River operate with the same technology first used more than 150 years ago; human power and gravity. Valves in the lock chambers are opened and closed by hand, and gravity empties or fills the chambers with water. No pumps or electricity are needed.